Many sizing and classifying methods employ gravity of solid material in hydrous slurry with an incoming feed containing the material encountering an upward teeter water flow. The variation in size and/or density will result in heavier particles failing to a lower level of the hindered-bed settler and lighter particles being uplifted to an overflow level of the hindered-bed settler thus affecting the desired separation.
The operation of so called hindered-bed settlers is based on even distribution of a controlled amount of teeter water into an in inner space of the body of the hindered-bed separator with teeter water distributor means arranged in the inner space of the body of the hindered-bed separator. Usually, the teeter water is pumped into teeter pipes of the teeter water distributor means from one side only, but if the water is “dirty” and contains for example fine solids much s, the teeter water pipes will get clogged because of the fine solids settling at the end of the teeter pipe where the flow velocity is lowest. Gradually this clogging then is proceeding towards the feed end of the teeter pipes and relatively soon the teeter water feed into the hindered-bed settler becomes biased and operation becomes poor. The hindered-bed settler has to be stopped for pipe cleaning meaning production losses etc. In some cases teeter water is pumped into the teeter pipes from both ends, but then the clogging starts from the middle of the teeter pipes.